Coronary Artery Stenosis in High-risk Patients: 64-Section CT and Coronary Angiography-Prospective Study and Analysis of Discordance

Purpose: To assess the diagnostic accuracy of multisection (64-section) computed tomography (CT) versus coronary angiography in detection of and assignment of grades for coronary artery stenoses in a high-risk population and to investigate causes for discordance between the two. Materials and Methods: The protocol was approved by the local ethics committee. Patients gave informed consent. The study included 114 patients (103 men, 11 women; mean age, 63 years +/- 8.2 [ standard deviation]) with potential myocardial ischemia. Multisection CT images were interpreted independently by two radiologists with unequal experience in reading coronary CT angiograms. Diagnostic performance of 64-section CT in detection of stenoses of 50% or more was assessed per patient, per artery, and per segment. Interrater agreement was assessed by using the Cohen kappa coefficient. Agreement between 64-section CT and coronary angiography for assigning grades to stenoses was assessed by using Bland-Altman analysis. Results: Sixty-eight percent of patients had stenoses of 50% or more. Good interrater agreement was found, with kappa values of 0.77-0.85. For the most experienced radiologist, the sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were 73.4%, 95.0%, 14.7, and 0.28 per segment, 95.2%, 94.7%, 18.0, and 0.05 per artery, and 100%, 89.2%, 9.26, and zero per patient, respectively. Discordance between 64-section CT and coronary angiography was related to either under-or overestimation of the degree of stenosis, anatomic misclassification, and coronary artery segments that were not assessable at 64-section CT. Bland-Altman analysis showed poor agreement, especially for intermediate stenosis (mean bias, 1.3%; 95% limits of agreement: -27.3%, 29.9%). Conclusion: Despite excellent sensitivity and negative likelihood ratios in a per-patient or per-vessel analysis, some coronary artery stenosis remained misdiagnosed with 64-section CT, resulting in limited sensitivity on a per-segment basis owing to anatomic discordance and failure to accurately quantify intermediate stenosis. (C) RSNA, 2009